Benefited from the advantage of high precision, wide area and low cost, the time transfer method based on precise point positioning (PPP) has become a popular technique for the remote clock comparisons. Although the time reference to which satellite clocks are referred can be eliminated by the difference between stations, the effect of satellite clock biases on the estimation of receiver clock offset is always ignored for PPP time transfer. Considering the PPP technique is extended from the all-in-view (AV) by the full use of precise carrier phase observables, a method to evaluate the effects of satellite clock biases on AV and PPP time transfer is proposed first. Then, the GPS, Galileo and BDS-3 time transfer results with different international GNSS Service (IGS) precise products are compared to verify the negative effects of satellite clock biases on AV and PPP time transfer. In our experiment, precise orbit and clock products provided by GFZ (German Research Centre for Geosciences), ESA (European Space Agency) and COD (Center for Orbit Determination in Europe) are used to obtain the clock comparison results of nine time links, including three short baselines, three medium baselines and three long baselines. The results show that the effects of satellite clock biases on AV and PPP time transfer are related to the magnitude of satellite clock biases and the baseline distance between stations. After removing the satellites with larger satellite clock biases, we assess the negative effects of satellite clock biases on AV and PPP time transfer for GPS, Galileo and BDS-3, respectively. By using GFZ, COD and ESA precise products for AV time transfer, the inconsistency of GPS and Galileo time transfer results caused by satellite clock biases is below 0.2 ns for long baseline. Due to the larger satellite clock biases for BDS-3, the inconsistency of BDS-3 AV time transfer results caused by satellite clock biases could reach 0.3 ns for medium baseline and even reach 0.9 ns for long baseline. For GPS and Galileo PPP time transfer, the inconsistency of time transfer results is below 0.05 ns for long baseline. However, the inconsistency of BDS-3 PPP time transfer results can only achieve 0.11 ns for medium baseline and 0.3 ns for long baseline. Thus, it is concluded that the satellite clock biases of BDS-3 precise satellite clock products need refining to improve the performance of BDS-3 PPP time transfer.

得益于精度高、面积广、成本低等优点，基于精确点定位（PPP）的时间传递方法已成为远程时钟比较的常用技术。尽管卫星时钟所引用的时间参考可以通过台站之间的差异来消除，但对于 PPP 时间传输，卫星时钟偏差对接收机时钟偏移估计的影响总是被忽略。考虑到PPP技术是通过充分利用精确的载波相位可观测物从全视角（AV）扩展而来的，首先提出了一种评估卫星时钟偏差对AV和PPP时间传输影响的方法。然后，将不同国际GNSS服务（IGS）精密产品的GPS、Galileo和BDS-3时间传递结果进行比较，验证卫星时钟偏差对AV和PPP时间传递的负面影响。在我们的实验中，利用德国地球科学研究中心（GFZ）、欧洲航天局（ESA）和欧洲轨道确定中心（COD）提供的精确轨道和时钟产品，得到了9个时间链接的时钟比较结果，包括3个短基线、3个中基线和3个长基线。结果表明，卫星时钟偏差对 AV 和 PPP 时间传输的影响与卫星时钟偏差的大小和站点之间的基线距离有关。在去除具有较大卫星时钟偏差的卫星后，我们分别评估了卫星时钟偏差对 GPS、Galileo 和 BDS-3 的 AV 和 PPP 时间传输的负面影响。通过使用 GFZ、COD 和 ESA 精密产品进行 AV 时间传输，卫星时钟偏差导致的 GPS 和 Galileo 时间传输结果的不一致小于 0。长基线为 2 ns。由于BDS-3的卫星时钟偏差较大，卫星时钟偏差导致BDS-3 AV时间传输结果的不一致在中基线下可达0.3 ns，在长基线下甚至可达0.9 ns。对于 GPS 和 Galileo PPP 时间传输，对于长基线，时间传输结果的不一致性低于 0.05 ns。然而，BDS-3 PPP 时间转移结果的不一致性在中等基线下只能达到 0.11 ns，在长基线下只能达到 0.3 ns。因此，得出结论，BDS-3 精密卫星钟差产品的卫星钟差需要改进，以提高 BDS-3 PPP 时间传输的性能。